我遇到使用GLKit着色PNG图像的问题。
我有一个白色的PNG图像,我加载到应用程序中,然后用它来创建纹理:
UIImage *image = [ UIImage imageNamed:@"brushImage" ];
NSError *error = nil;
texture_m = [[ GLKTextureLoader textureWithCGImage:image.CGImage options:nil error:&error] retain ];
if (error) {
NSLog(@"Error loading texture from image: %@",error);
}
创建纹理时没有错误。
然而,当我想要激活混合渲染纹理时,颜色似乎被忽略,我得到一个白色图像。我在OpenGL1中执行此操作时没有任何问题,因为图像会拾取glColor4f()
中定义的颜色。这是我的渲染代码:
-(void)render{
if (texture_m != nil) {
effect_m.texture2d0.enabled = GL_TRUE;
effect_m.texture2d0.envMode = GLKTextureEnvModeReplace;
effect_m.texture2d0.target = GLKTextureTarget2D;
effect_m.texture2d0.name = texture_m.name;
}
[effect_m prepareToDraw];
glClear(GL_COLOR_BUFFER_BIT);
GLfloat squareVertices[] = {
50, 50,
150, 50,
50, 150,
150, 150
};
GLfloat squareTexture[] = {
0, 0,
1, 0,
0, 1,
1, 1
};
glColor4f( 1, 0, 0, 1 );
glEnableVertexAttribArray(GLKVertexAttribPosition);
glEnableVertexAttribArray(GLKVertexAttribTexCoord0);
glEnable(GL_BLEND);
glBlendFunc( GL_ONE, GL_ONE_MINUS_SRC_ALPHA );
glVertexAttribPointer(GLKVertexAttribPosition, 2, GL_FLOAT, GL_FALSE, 0, squareVertices);
glVertexAttribPointer(GLKVertexAttribTexCoord0, 2, GL_FLOAT, GL_FALSE, 0, squareTexture );
glDrawArrays(GL_TRIANGLE_STRIP, 0, 4);
glDisable(GL_BLEND);
glDisableVertexAttribArray(GLKVertexAttribPosition);
glDisableVertexAttribArray(GLKVertexAttribTexCoord0);
}
任何人都可以帮忙解决这个问题 感谢
礼
答案 0 :(得分:2)
我设法解决了我的问题,这是解决方案
-(void)render
{
if (texture_m != nil) {
effect_m.texture2d0.enabled = GL_TRUE;
// here you need to env mode to GLKTextureEnvModeModulate rather than GLKTextureEnvModeReplace
effect_m.texture2d0.envMode = GLKTextureEnvModeModulate;
effect_m.texture2d0.target = GLKTextureTarget2D;
effect_m.texture2d0.name = texture_m.name;
}
// then here I have added the tint colour to the GLKBaseEffect class as constant colour which I imagine replaces the calls to glColor4f for OpenGL1.1
effect_m.useConstantColor = YES;
float alphaValue = 0.7;
GLKVector4 colour = GLKVector4Make( 0* alphaValue, 1* alphaValue, 1* alphaValue, alphaValue );
effect_m.constantColor = colour;
// remember multiplying the alpha value to each colour component
[effect_m prepareToDraw];
glClear(GL_COLOR_BUFFER_BIT);
GLfloat squareVertices[] = {
50, 50,
150, 50,
50, 150,
150, 150
};
GLfloat squareTexture[] = {
0, 0,
1, 0,
0, 1,
1, 1
};
// glColor4f not necessary
// glColor4f( 1, 0, 0, 1 );
glEnableVertexAttribArray(GLKVertexAttribPosition);
glEnableVertexAttribArray(GLKVertexAttribTexCoord0);
glEnable(GL_BLEND);
glBlendFunc( GL_ONE, GL_ONE_MINUS_SRC_ALPHA );
glVertexAttribPointer(GLKVertexAttribPosition, 2, GL_FLOAT, GL_FALSE, 0, squareVertices);
glVertexAttribPointer(GLKVertexAttribTexCoord0, 2, GL_FLOAT, GL_FALSE, 0, squareTexture );
glDrawArrays(GL_TRIANGLE_STRIP, 0, 4);
glDisable(GL_BLEND);
glDisableVertexAttribArray(GLKVertexAttribPosition);
glDisableVertexAttribArray(GLKVertexAttribTexCoord0);
}